 |
|
'Natural' nitrogen-fixing bacteria protect soybeans from aphids
April 15, 2009An invasion of soybean aphids poses a problem for soybean farmers requiring application of pesticides, but a team of Penn State entomologists thinks a careful choice of nitrogen-fixing bacteria may provide protection against the sucking insects.
Soybeans are legumes, plants that can have a symbiotic relationship with nitrogen-fixing bacteria -- rhizobia -- and therefore do not need additional nitrogen fertilizer. Each type of legume -- peas, beans, lentils, alfalfa -- have their own rhizobia.
"Soybeans are from Asia and so there were originally no nitrogen-fixing bacteria that would colonize soybeans in U.S. soils," said Consuelo De Moraes, associate professor of entomology. "The rhizobia had to be transferred here."
The soybean aphid is also not native to North America. This pest only began to infest soybean fields about 10 years ago but are now fully established pests requiring pesticide applications to avoid the loss of as much as 40 percent of the crop. The researchers investigated the relationship between the type of rhizobia colonizing soybean plants and the plants' infestation with the aphids.
"Our results demonstrate that plant-rhizobia interactions influence plant resistance to insect herbivores and that some rhizobia strains confer greater resistance to their mutualist partners than do others," the researchers report in the journal Plant and Soil online.
They looked at soybean plants inoculated with the rhizobia provided by the inoculant company; without rhizobia, but with added nitrogen fertilizer, and by existing rhizobia in the soil.
"The bacteria that were used initially to inoculate the first crops of soybeans are growing wild in the soil now," said Mark C. Mescher. "They are now considered "naturally occurring" and are different from the inoculants purchased with the soybean seeds."
They become natural because they change through generations of contact with other rhizobia. While they may not provide as much nitrogen to the plant as commercial types, the trade off between optimal growth and heavy insect damage may still be worthwhile.
"In most cases, the inoculant companies provide rhizobia for inoculation that gives plants the maximum yield," said Jennifer M. Dean, postdoctoral fellow in entomology. "Their rhizobia are highly competitive against naturally occurring nitrogen-fixing bacteria. The inoculant companies treat the natural rhizobia almost as a pest."
Because of this, soybeans almost uniformly incorporate the specially developed rhizobia rather than the natural ones. However, the researchers found that the plants associated with the naturally occurring rhizobia had lower aphid densities than either the artificially fertilized plants or the plants inoculated with commercial rhizobia. They also found the same level of nitrogen in both soybean plants inoculated with natural rhizobia and those inoculated with commercial varieties.
"This is the first time anyone has shown how different strains of rhizobia can effect herbivory," said De Moraes. "This may be another tool to use to protect plants from insect herbivory. It may also be applicable to other legumes."
The researchers do not yet know what the natural nitrogen-fixing bacteria do to repel aphids.
"It is really exciting to see that the nitrogen producing rhizobia can be protective," said Dean. "Next we want to isolate rhizobia strains from the fields and look for the specific mechanism of how they repel the aphids."
Penn State
The soybean aphid is also not native to North America. This pest only began to infest soybean fields about 10 years ago but are now fully established pests requiring pesticide applications to avoid the loss of as much as 40 percent of the crop. The researchers investigated the relationship between the type of rhizobia colonizing soybean plants and the plants' infestation with the aphids.
"Our results demonstrate that plant-rhizobia interactions influence plant resistance to insect herbivores and that some rhizobia strains confer greater resistance to their mutualist partners than do others," the researchers report in the journal Plant and Soil online.
They looked at soybean plants inoculated with the rhizobia provided by the inoculant company; without rhizobia, but with added nitrogen fertilizer, and by existing rhizobia in the soil.
"The bacteria that were used initially to inoculate the first crops of soybeans are growing wild in the soil now," said Mark C. Mescher. "They are now considered "naturally occurring" and are different from the inoculants purchased with the soybean seeds."
They become natural because they change through generations of contact with other rhizobia. While they may not provide as much nitrogen to the plant as commercial types, the trade off between optimal growth and heavy insect damage may still be worthwhile.
"In most cases, the inoculant companies provide rhizobia for inoculation that gives plants the maximum yield," said Jennifer M. Dean, postdoctoral fellow in entomology. "Their rhizobia are highly competitive against naturally occurring nitrogen-fixing bacteria. The inoculant companies treat the natural rhizobia almost as a pest."
Because of this, soybeans almost uniformly incorporate the specially developed rhizobia rather than the natural ones. However, the researchers found that the plants associated with the naturally occurring rhizobia had lower aphid densities than either the artificially fertilized plants or the plants inoculated with commercial rhizobia. They also found the same level of nitrogen in both soybean plants inoculated with natural rhizobia and those inoculated with commercial varieties.
"This is the first time anyone has shown how different strains of rhizobia can effect herbivory," said De Moraes. "This may be another tool to use to protect plants from insect herbivory. It may also be applicable to other legumes."
The researchers do not yet know what the natural nitrogen-fixing bacteria do to repel aphids.
"It is really exciting to see that the nitrogen producing rhizobia can be protective," said Dean. "Next we want to isolate rhizobia strains from the fields and look for the specific mechanism of how they repel the aphids."
Penn State
Aphids Current Events and Aphids News RSSScientists discover how to send insects off the scent of crops
Biotechnology and Biological Sciences Research Council (BBSRC)-funded research, published this week in Chemical Communication, describes how scientists have discovered molecules that could confuse insects' ability to detect plants by interfering with their sense of smell. This could reduce damage to crops by insect pests and contribute to food security.
ISU researchers study insecticide-free method for control of soybean aphids
Two Iowa State University researchers are examining a new method of controlling soybean aphids without the use of chemical pesticides.
'Killer spices' provide eco-friendly pesticides for organic fruits and veggies
Mention rosemary, thyme, clove, and mint and most people think of a delicious meal. Think bigger-acres bigger.
Why are autumn leaves red in America and yellow in Europe?
Walking outdoors in the fall, the splendidly colorful leaves adorning the trees are a delight to the eye. In Europe these autumn leaves are mostly yellow, while the United States and East Asia boast lustrous red foliage.
Discovering soybean plants resistant to aphids and a new aphid
This year farmers in the Midwest are growing a new variety of soybeans developed by University of Illinois researchers that has resistance to soybean aphids.
Gene developed through conventional breeding to improve cowpea aphid resistance
The cowpea or black-eyed pea, as it is more commonly known, is a New Year's tradition for good luck. But disease and particularly aphids, which can wreck a crop within a few a days, are especially bad luck for the cowpea, according to scientists.
How social insects recognize dead nestmates
When an ant dies in an ant nest or near one, its body is quickly picked up by living ants and removed from the colony, thus limiting the risk of colony infection by pathogens from the corpse.
Small investments to battle soybean pest paying off big, says MSU researcher
The small amount of money put toward fighting the tiny, yet destructive soybean aphid will pay big dividends in the coming years, said a Michigan State University economist, thanks to a research and outreach system developed during the last 50 years.
Study predicts when invasive species can travel more readily by air
Global airlines be forewarned: June 2010 could be a busy month for invasive plants, insects and animals seeking free rides to distant lands.
Grazing animals help spread plant disease
Researchers have discovered that grazing animals such as deer and rabbits are actually helping to spread plant disease - quadrupling its prevalence in some cases - and encouraging an invasion of annual grasses that threaten more than 20 million acres of native grasslands in California.
More Aphids Current Events and Aphids News Articles
 |
Aphid Chaser by SpringStar LLC Ward off pest aphids on roses with a natural pheromone that alarms aphids and causes them to stop feeding and eventually move on or die of starvation. Non-toxic dispensers do not affect beneficial insects and control most prevalent aphid types, especially Green Peach Aphid, the most common species that attacks roses. One dispenser hung on each infested rose plant wards off aphids in 5 to 7 days. Dispensers work for 3 to 4 weeks. Apply dispensers early in the season to prevent aphid colonies from becoming established. Package contains 4 individually wrapped dispensers, enough for one full season. |
 |
Host Plant Catalog of Aphids: Palaearctic Region (Springer Reference) by Jaroslav Holman (Author) The major part of this Catalog presents host lists of particular aphid species in the Palaearctic Region based on published data and more than 2,400 author’s unpublished host records, with respective references arranged by geographical provenance. The book includes separate lists of aphids living on particular plants, arranged in alphabetical order of plant families and genera, separately for mosses, ferns, gymnosperms, dicotyledons and monocotyledons. The coverage is exhaustive, including some 3,706 aphid species (about 80 per cent of the aphid fauna of the world), feeding on 11,131 species of host plants in 1,948 genera and 243 families. Host Plant Catalog of Aphids combines well-organized data with up-to-date information on geographic distribution of particular aphid... |
 |
Skandy Aphid Moon (Primary Contributor) |
 |
Hi Driver by Aphid Moon |
 |
3" button / pin printed with green, aphid, insect, beetle, wings by Shopzeus Customized 3" button / pin. |
 |
Teva Womens Psuedo Aphid Casual shoe Sz: 6.5 by Teva Teva doesn't try to fake it with this stylish, very comfortable sporty casual. Soft, waterproof nubuck upper in a casual athletic style, with contrast stitching, overlay and Teva logo detail, center seam contrasting stripe, arch band with Velcro® closure and elasticized, padded collar. Soft fabric lining, cushioned insole with Shoc Pad® heel pad. Shock absorbing flexible Mush® EVA midsole. Geometric traction patterned outsole with aggressive wrap at toe, side and heel. |
 |
Teddy Bear with bug, wingless, green, aphid, insect t-shirt by SHOPZEUS 7 inch tall soft teddy bear with personalized white t-shirt. |
 |
Onesie with plant, aphid, insect, beetle, eating by SHOPZEUS |
 |
Star Birth EP Various Artists (Primary Contributor) |
 |
Decorated Mouse Pad with green, aphid, insect, antennae, bug by SHOPZEUS Professional "Brite White" fabric mouse pads are among the most versatile and durable, providing brilliant graphic reproduction for spot color or full color imprints. This durable polyester surface is above industry standards and provides a superior product value overall. Designed to reproduce vibrant detailed images. Our mouse pads have white fabric top with the 100% genuine black rubber base (not the cheap foam your seen on other advertisements). |
| © 2009 BrightSurf.com |